|
|
Characterization of carrageenan by densitometry
Poledňáková, Halina ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
The density of the carrageenan solution was investigated by densitometry depending on temperature and concentration. Subsequently, ultrasonic velocity was examined using densitometry and high-resolution ultrasonic spectroscopy. The measurements were executed using aqueous and sodium chloride solutions of carrageenan in a broad range of concentrations. It was found that the carrageenan samples are not liable to irreversible changes of density and ultrasonic velocity in dependence on temperature and concentration . Furthermore, it was proved that carrageenan in both mediums is stable, the samples do not exhibit degradation or changes in the properties of the ionic strength effect.
|
|
|
Temperature dependence of carrageenan and hyaluronan solutions
Poledňáková, Halina ; Smilek, Jiří (referee) ; Hurčíková, Andrea (advisor)
This diploma thesis focuses on the study of temperature dependence of -carrageen, hyaluronan of low molecular weight (250–450 kDa) and hyaluronan of high molecular weight (1 500–1 750 kDa) in aqueous solutions. The description of temperature depending changes in properties of these substance is based on rheological method. This work concentrates on the characterization of viscoelasticity through measurement of the storage (elastic) and loss (viscous) modulus using -carrageen and hyaluronan solutions of different molecular weights and different concentrations depending on temperature (20–50 °C, alternatively, in carrageen, 20–80 °C). The temperature dependence was further measured using an uncommon technique called high resolution ultrasonic spectroscopy (HR-US) which measured relative velocity of selected concentrations of -carrageen and hyaluronan of high molecular weight depending on the temperature of heating and cooling (20–80 °C). The measurements of temperature dependence were carried out for varied oscillation frequencies of rheometer sensor/frequency of ultrasonic waves. Knowledge of temperature dependence of the investigated substances may be applied in drug chemistry, primarily with respect to degradation due to high temperatures. The measured data gives information about sol-gel temperature and gel-sol temperature of carrageen.
|
|
|
Characterization of medical biopolymers by ultrasound spectroscopy
Jugl, Adam ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
Using high resolution ultrasonic spectroscopy has been investigated hyaluron solutions of various molecules weights depending on their concentration and solution temperature. Furhermore, the influence of ionic strenght on the properties of solutions by dissolving hyaluronan in 0.15 M aqueous solution of sodium chloride. For comparison the properties of the hyaluronan solutions were compared with aqueous solutions of carrageenan. It was found that hyaluronan in solution behaves the same, regardless of the weight, temperature and concentration.
|
|
|
Electrode Materials for Li-S Batteries
Jaššo, Kamil ; Almáši,, Miroslav (referee) ; Syrový,, Tomáš (referee) ; Kazda, Tomáš (advisor)
This thesis is focused on the research of electrode materials for lithium-sulphur (Li-S) batteries, with an emphasis on the optimization of the process of preparation of positive electrodes through the modification of the individual technical steps of the manufacturing process and the selection of a suitable binder. The theoretical part of the thesis is devoted to terminology and battery issues with emphasis on Li-S batteries, their working principle, shortcomings, critical parameters for commercialization and existing research in this field. The practical part of the thesis deals with the influence of the compression pressure used in the production of positive electrodes on the electrochemical properties of the resulting Li-S cells. In the next part of the thesis, the influence of the binder used on the resulting electrochemical properties is investigated. In the following sections, the influence of the thickness of the electrode material layer and the ratio of its individual components (C/S) on the resulting electrochemical properties of the Li-S cell is analyzed. On the basis of the measured results, the optimum conditions for the preparation of the positive electrodes of the Li-S cells have been identified with respect to the individual technical steps of the manufacturing process.
|
|
|
Temperature dependence of carrageenan and hyaluronan solutions
Poledňáková, Halina ; Smilek, Jiří (referee) ; Hurčíková, Andrea (advisor)
This diploma thesis focuses on the study of temperature dependence of -carrageen, hyaluronan of low molecular weight (250–450 kDa) and hyaluronan of high molecular weight (1 500–1 750 kDa) in aqueous solutions. The description of temperature depending changes in properties of these substance is based on rheological method. This work concentrates on the characterization of viscoelasticity through measurement of the storage (elastic) and loss (viscous) modulus using -carrageen and hyaluronan solutions of different molecular weights and different concentrations depending on temperature (20–50 °C, alternatively, in carrageen, 20–80 °C). The temperature dependence was further measured using an uncommon technique called high resolution ultrasonic spectroscopy (HR-US) which measured relative velocity of selected concentrations of -carrageen and hyaluronan of high molecular weight depending on the temperature of heating and cooling (20–80 °C). The measurements of temperature dependence were carried out for varied oscillation frequencies of rheometer sensor/frequency of ultrasonic waves. Knowledge of temperature dependence of the investigated substances may be applied in drug chemistry, primarily with respect to degradation due to high temperatures. The measured data gives information about sol-gel temperature and gel-sol temperature of carrageen.
|
|
|
Characterization of carrageenan by densitometry
Poledňáková, Halina ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
The density of the carrageenan solution was investigated by densitometry depending on temperature and concentration. Subsequently, ultrasonic velocity was examined using densitometry and high-resolution ultrasonic spectroscopy. The measurements were executed using aqueous and sodium chloride solutions of carrageenan in a broad range of concentrations. It was found that the carrageenan samples are not liable to irreversible changes of density and ultrasonic velocity in dependence on temperature and concentration . Furthermore, it was proved that carrageenan in both mediums is stable, the samples do not exhibit degradation or changes in the properties of the ionic strength effect.
|
|
|
Characterization of medical biopolymers by ultrasound spectroscopy
Jugl, Adam ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
Using high resolution ultrasonic spectroscopy has been investigated hyaluron solutions of various molecules weights depending on their concentration and solution temperature. Furhermore, the influence of ionic strenght on the properties of solutions by dissolving hyaluronan in 0.15 M aqueous solution of sodium chloride. For comparison the properties of the hyaluronan solutions were compared with aqueous solutions of carrageenan. It was found that hyaluronan in solution behaves the same, regardless of the weight, temperature and concentration.
|
guest ::
